Radiofrequency filters often have a number of connected cavities whose shape and dimensions are chosen so as to filter signals in desired frequency ranges (e.g., radiofrequency or microwave frequencies). The body housing of the substrate that defines the cavities is often made of aluminum. Compared to other metals, aluminum has a low density (about 2.7 gm/cm3), low coefficient of thermal expansion (e.g., about 30×10−6 m/m° C. or about 30 ppm/° C.), and low cost.